New iPad has a charging problem: DisplayMate

Mar 28, 2012

The new iPad.

Are you damaging your new iPad just by charging it? That seems to be what Apple is suggesting in response to questions about whether the third-generation iPad continues to charge even after the battery indicator reads 100 per cent.

Last week, DisplayMate Technologies reported discrepancies between the charge indicator and the power available. According to DisplayMate President Raymond Soneira, if you stop charging the iPad when the indicator reads 100 per cent, you're really only about 90 per cent charged. This means you probably won't get the maximum running time you'd expect from a fully charged device.

To get a full charge, Soneira wrote, iPad owners would have to leave the it plugged in for about an hour more. He discovered the issue while doing extensive testing of the new iPad's retina display. During benchmarking, he measured the actual power drawn by the AC adapter.

"There is something wrong with the battery charge mathematical model on the iPad," Soneira wrote. "It should not say 100 per cent until it actually stops recharging."

It was noted earlier that the third-generation iPad does take longer to charge than the iPad 2 because of its 70 per cent-larger, 42.5-watt-hour battery, needed to support the sharper display on the newer iPad. The battery also doesn't charge when the iPad is plugged in while it's being used for graphics-heavy gaming and video watching.

So what does this "undercharging" really mean? Should you just charge it up for another hour or leave it plugged in overnight?

"Apple is saying ... if you charge it more than [when the battery indicator reads 100 per cent], you could actually harm the longevity of the battery," CNBC's Jon Fortt reported.

Soneira wrote in response to Apple's assertion that, "Damaging the longevity of the battery is then exactly what the new iPad's internal battery charging hardware and software are doing since it is their responsibility to properly control and manage the battery charging process. It's pretty obvious that if the new iPad knows that it is fully charged then it should automatically stop the charging!"

ZDNet says, however, that the battery is actually performing just as it should: "Charging circuits employ a number of tricks to help keep the battery safe and healthy. The first trick is to slow the rate of charging as the battery reaches its full capacity so as to avoid the risk of overcharging. ... This is deliberate and it’s purpose is to protect your battery - and you - from damage."

If you maintain your iPad battery properly, it should keep up to "80 per cent of its original capacity at 1000 full charge and discharge cycles," according to Apple's website.

As this issue continues to get more digital ink and airtime, you can bet we likely soon see an update to close the gap between the charging buffer and reality.